Photographic film assemblage

ABSTRACT

A film pack for use in an in-camera processing system comprising a container in which a plurality of individual film units, each including a light-sensitive film and an image-receiving sheet coupled by means including a leader, a pull tab connected to said leader, are arranged in stacked relation so that after the film of each unit is exposed it can be moved into superposed relation with its corresponding image-receiving sheet for processing when the pull tab extending from the container, and camera it is associated with, is pulled. The pull tabs of all of the film units are folded back upon themselves and interleaved with the film units so as to be confined wholly within the container until they are pulled successively therefrom by pulling on the pull tab of the preceding film unit. The pull tab on the first film unit is adhered to a safety cover sheet which is wrapped around the stack of film units to protect them against being fogged during handling of a pack outside of the camera, and is withdrawn from the pack and the camera after the pack is placed in the camera to ready the first film unit for exposure. To permit ready assemblage of the film units, the pull tabs are provided with patches or stripes of a cohesive adhesive material so arranged that the pull tabs become adhesively connected together, and the pull tab of the first film unit becomes adhesively connected to the safety cover sheet, with bonds having the necessary shear and peel strengths by the mere application of pressure to the stack of film units after the pull tabs have been folded back into interleaved relation with the film units.

United States Patent Moulton et al.

[54] PHOTOGRAPHIC FILM ASSEMBLAGE [72] Inventors: Richard D. Moulton, Rochester, I N.Y.; Stanley R. Schieven, deceased, late of Webster, NY. by Arline E.

Schieven, executrix [73] Assignee: Eastman Kodak Company,

Rochester, N.Y.

[22] Filed: Feb. 11, 1971 211 Appl. No.: 114,446

[52] US. Cl. ..95/19, 96/76 R [51] Int. Cl. ..G03b 19/10 [58] Field of Search ..95/13, 19, 22; 96/76 R [56] Resumes Cited UNITED STATES PATENTS 2,477,304 7/1949 Land ..95/13 3,080,805 3/1963 Hamilton ....95/13 3,l l3,496 12/1963 Eburn et al ..95/13 Primary Examiner-Samuel S. Matthews Assistant ExaminerFred L. Braun Attorney-William T. French, Karl T. Naramore and Robert F. Crocker [S 7] ABSTRACT A film pack for use in an in-camera processing system comprising a container in which a plurality of in- [451 Dec. 26, 1972 dividual film-units, each including a light-sensitive film and an image-receiving sheet coupled by means including a leader, a pull tab connected to said leader, are arranged in stacked relation so that after the film of each unit is exposed it can be moved into superposed relation with its corresponding image-receiving sheet for processing when the pull tab extending from the container, and camera it is associated with, is pulled. The pull tabs of all of the film units are folded back upon themselves and interleaved with the film units so as to be confined wholly within the container until they are pulled successively therefrom by pulling on the pull tab of the preceding film unit. The pull tab on the first film unit is adhered to a safety cover sheet which is wrapped around the stack of film units to protect them against being fogged during handling of a pack outside of the camera, and is withdrawn from the pack and the camera after the pack is placed in the camera to ready the first film unit for exposure.

To permit ready assemblage of the film units, the pull tabs are provided with patches or stripes of a cohesive adhesive material so arranged that the pull tabs become adhesively connected together, and the pull tab of the first film unit becomes adhesively connected to the safety cover sheet, with bonds having the necessary shear and peel strengths by the mere application of pressure to the stack of film units after the pull tabs have been folded back into interleaved relation with the film units,

9 Claims, 9 Drawing Figures PATENTEDBEcz I912 3.10m 1? sum 3 [1F 3 R/CHARD 0. MOUL TON STANLEY/1?. SCH/EVEN,

deceased by A/PL/IVE E. SCH/E W. N EXECUTE/X INVENTORS A rromver 1 PHOTOGRAPHIC FILM ASSEMBLAGE This invention relates to photography and more particularly to a novel assemblage of film units adapted for use in an in-camera processing system wherein a positive print is obtained by an image-transfer process.

Film units used in the well known in-camera processing system generally consist of a photosensitive sheet element which is normally first exposed and then biased into superposed relation with a second sheet element which is, in general, photographically inert and aids in the control of distributionof the processing fluid between the two sheets. The photosensitive element may contain an integral print-receiving stratum or, more preferably, the second sheet element comprises a transfer image-receiving element. After the photosensitive sheet element has been photographically exposed the two sheet elements are biased into face-to-face relation and moved to, and between, a pair of opposed pressure-applying members, such as a pair of parallel rollers in a camera which are spring loaded into engagement with one another. Application of pressure to a frangible fluid retaining pod situated between the sheet elements adjacent their leading edges effects controlled rupture of the pod and a predetermined distribution of its processing fluid contents between, and in contact with, the opposed surfaces of the superposed sheet elements. Subsequent to transfer processing, the image-carrying area of the print-receiving sheet may be separated from the laminate.

For use in a camera, a plurality of these film units, usually eight, are assembled in a pack which when placed in the back of the camera allows eight pictures to be made in succession. As shown in US. Pat. No. 3,161,516 the several film units are arranged in a container with the light-sensitive sheets of all of the film units stacked on one side of a pressure plate and facing an exposure aperture, whereas the image-receiving sheets of all the film units are stacked on the other side of the pressure plate. The light-sensitive sheet and image-receiving sheet of each film unit are connected together so that when a pull tab attached thereto is pulled through and from the camera it advances the lead end of the exposed film unit between the pressureapplying means of the camera to an extent that said leading end may be grasped for withdrawing the film unit from the camera and between the pressure-applying means. The pull tabs of the several film units are adhered to one another so that when the pull tab of one film unit is pulled to withdraw the leading end of its film unit between the pressure-applying means of the camera it pulls the end of the pull tab attached to the succeeding film unit out of the camera so that it is accessible for initiating the withdrawal of the next film unit after its exposure.

In the noted prior art film pack the pull tabs of all of r the film units extend outside of the pack so that no This disadvantage may be overcome if the film units are assembled within the pack container in such a manner that all of the pull tabs lie within the container until they are pulled therefrom by pulling on the end of one of the preceding film units, as shown in co-pending US. application Ser. No. 841,865 filed July 15, 1969, now abandoned. In such afilm unit assemblage the pull tab of the first film unitshould be adhered to the safety cover sheet, which is wrapped around the stack of film units to protect them against being fogged during handling outside of the camera, and is withdrawn from the pack and camera after the pack is placed in the camera and the safety cover is pulled out of the camera to ready the first film unit for exposure.

While this last mentioned type of film unit assemblage is a decided improvement over the earlier type above-mentioned so far as loading of the pack into the camera is concerned, the fact that the pull tabs must be folded back and interleaved with the several film units, and must be selectively adhered to one another while thefilm units are in stacked relation, presents an assembly problem which the present invention overcomes.

The primary object of the present invention is to provide an assemblage of film units of the type described wherein the pull tabs of each of the several film units is folded back upon itself and interleaved within the film units so as to be confined within the pack, and wherein the pull tabs are so constructed that they can be selectively adhered to one another while the film units are in this stacked relation merely by the application of pressure to the stack at a prescribed area which will not adversely effect any component of the assemblage.

Another object is to provide an assemblage of film units wherein the pull tabs are provided with patches or strips of a self adhering, or cohesive, adhesive material so arranged that the pull tabs become adhesively connected together with bonds having the desired shear and peel strengths by the mere application of pressure to the stack of film units after the pull tabs have been folded back into interleaved relation with the remainder of the film units.

A further object is to provide an assemblage of film units of the type described which is so constructed that it can be readily produced by an automatic or a semiautomatic machine or manually.

The novel features that we consider characteristic of our invention are set forth with particularity in the appending claims. The invention itself, however, both as to its organization and its methods of operation, together with additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings in which:

FIG. 1 is a perspective view showing how a photographic film unit is folded when assembled in a film pack constructed in accordance with the present invention;

FIG. 2 is a plan view of the film unit of FIG. 1;

FIG. 3 is a perspective view of a film pack comprising an assemblage of film units of the types shown in FIGS. 1 and 2;

FIG. 4 is an enlarged longitudinal sectional view taken substantially midway between the sides of the pack shown in FIG. 3;

' tabs and how adjacent pull tabs are connected together in accordance with a preferred embodiment of the present invention; FIG. 7 is a longitudinal section of a pull tab on an exaggerated scale to show a preferred arrangement of cohesivepatches and slip or release coats as applied thereto in accordance with the preferred form of the present invention;

FIG. 8 is a view similar to FIG. 6 but showing anothe arrangement of cohesive patches on the pull tab; FIG. 9 is a view similar to FIG. 8 but showing still another arrangement of cohesive patches on the pull tab.

Briefly, in the film assemblage or pack of the present v invention a plurality, usually eight (8), film units are arranged in stacked relation within a container having an opening at one end'through which the leading end of the individual units are pulled in succession by means of a pull tab connectedto each film unit. This brings a leader on each film unit through the pressure members of a camera which is then grasped and pulled to withdraw the film unit from the camera and spreads a processing solution over the exposed photosensitive sheet to causeprocessing' of the exposed image. The pull tabs of the several units are connected to one another so that when the one connected to an exposed unit is pulled from the pack and camera to initiate processing thereof, the pull tab of the next film unit is withdrawn from the camera to be accessible. In the present film pack the film units are so assembled that all of the pull tabs are confined within the pack for the purpose of facilitating the loading of the pack into the camera. To this end, the free end of each pull tab, except the one connected to the first film unit to be exposed, is folded back upon itself and around the end of the film unit to which it is attached and a portion thereof is adhered in faceto-face relationship with a portion of the preceding pull tab intermediate between the two ends of the preceding pull tab. The pull tab for the first film unit is adhered in a similar fashion to a portion of a safety cover for the pack. This means that when the film units are assembled in the pack the point of attachment for all pull tabs, except that one connected to the safety cover, are interleaved between the film units. In order to facilitate assembly of the packs,

the attachment of the pull tabs to one another and the safety cover are made by cohesive patches so arranged on the respective pull tabs that the pull tabs can be selectively attached together after the film units have been assembled in stacked relation by merely applying pressure to the stack of film units at points in alignment with the points of attachment between the pull tabs of the film units and the safety cover sheet.

Reference is now made to FIGS. 1-4 wherein there is illustrated a pack-type film unit and an assemblage of such units in the form of a film pack assembled according to the present invention. Each film unit, designated 10, comprises a generally rectangular photosensitive sheet 11 (hereinafter sometimes referred to as afilm) and a receiving sheet 12 (hereinafter sometimes referred to as the'receiver). Both of these sheets comprise a support which is opaque to light actinic to the photosensitive material on the film. Secured on the face of,- and extending along each of the lateral edges of, the film is a narrow spacer rail 13 in theifo'rm of a strip of thin paper. As will be described hereinafter, these spacer rails cooperate with-a part of the carriersheet for the receiver in spreading a .controlled thickness of processing solution between the sheets.

' The second, or print-receiving sheet may merely serve to aid in the distribution of a processing solution in contact with the photosensitive layer of the film, or, in the preferred form of thefilm unit, comprisesmeans for supporting atransfer image formed, for example, by

a silver halide diffusion, transfer reversal-process. At-' tached to the leading edge of the film 11 is a leader sheet 14 having a first section 15 approximately equal in width to the film and having a tapered end section 16. The transverse edge of the first section 15 is coupled to the leading edge of the film 11 as indicated at 17, and a rupturable fluid-containing pod 18 is mounted on leader sheet 14 ahead of the leading endof the film. The receiver sheet 12is mounted on a carrier sheet 19 having an intermediate section 20 approximately equal in width to receiver sheet 12 and having a generally rectangular opening 21 therein defining the area of the receiver sheet in which the image formation occurs. Those portions of the intermediate section 20 bordering on opening 21 provide a mask for defining the area of the image transferred from the film to the receiver. The narrow portion 22 of the carrier sheet extending along the lateral edge of the receiver cooperates with the spacer rails 13 in spreading a controlled thickness of a processing fluidbetween the two sheets. Carrier sheet 19 includes a leading end section 23 having a tapered end section 24 similar to tapered end section 16 and secured thereto behind the leading end of the tapered end section 16 as indicated at 17'.

Tapered end section 16 and portion 24 cooperate todefine the leading end section of the film unit which is advanced between pressure applying members of a camera.

The length'of leader sheet 14 between the leading edge of the film l1 and the point of attachment of the leader sheet to carrier sheet 19 is substantially equal to the length of the carrier sheet -19 between the point of attachment to the leader sheet and the leading edge of the receiver sheet 12. It is by virtue of this attachment that the film 11 and the receiver sheet 12 are capable of being biased into superposed registered relation during the processing of the film unit.

For trapping theexcess processing fluid an embossed trap 25 is attached to the trailing end of the carrier sheet 19. When the receiver sheet 12 and film 11 are biased into superposed relation for processing the film unit, the trap 25 is superposed with the trailing end of the film 11. The protuberances on the trap are (collectively). strong enough to separate the pressure rolls of the camera as the film unit is pulled between them for processing thus leaving a space between the film and closed more in detail in co-pending U.S. Pat. application Ser. No. 841,865 filed July 15, 1969 having an assignee in common with the present application and to which reference can be had for a more detailed description thereof. However, since the trap construction forms no part of the present invention the brief description given thereof is believed to be sufficient to an understanding of its function. So far as the present invention is concerned a film trap of the type shown in U.S. Pat, No. 2,686,717 could be used in the film unit.

Distribution of the processing fluid is effected by advancing the film 11 and receiver 12 and the pod of processing solution between a pair of juxta-posed pressure-applying members forming a part of the camera in which the film unit is to be exposed. The members apply compressive pressure to the film and receiver sheets progressively, from the leading ends in the area of the pod to the trailing ends, to cause the ejection of the fluid contents of the pod between the film and receiver sheets and the spreading of the fluid in a layer between and in contact with the sheets. The superposed spacer rails 13 and the narrow portions 22 of the carrier sheet 19 keep the processing solution from leaking out the edges of the film unit and their combined thickness determines the thickness of the layer of processing fluid which is spread between the image area of the film and receiver sheets 11 and 12 respectively. The excess processing fluid, which is always provided in the pod, is effectively collected and retained at the trailing end of the film unit by the trapping means 25.

A film pack or assemblage of film units is shown in FIGS. 3,4 and 5. For reasons of simplicity only two film units and the safety cover are shown in the pack, and inFIG. 5 the elements are shown in expanded relation to more clearly illustrate the manner in which the pull tabs are attached to one another and the safety cover sheet according to the present invention. The film pack, designated at 38, comprises a generally parallelepiped-shaped container or box 39 for holding and enclosing a plurality of film units 10 when each is folded upon itself as generally indicated in FIG. 1. Container 39 comprises a body portion having a forward wall 40, side walls 41,v a trailing end wall 42 and a leading end wall 43. Forward wall 40 is provided with a generally rectangular exposure aperture 44 for exposing the film 11- of the film units 10 carried within the container. Leading end wall 43 extends only part way of the depth of the container to provide a passage 45 at the leading end of the container through which the film units can be drawnfrom the container one at a time. The container is closed by a metal cover 46 having flanges 47 turned down along its sides and rear end to slidably engage side wall 41 and the trailing end wall 42 That portion of the leader sheet 14 between the leading edges of the film 11 and the pod 18 is bent back upon itself, and the carrier sheet 19 is similarly bent back upon itself adjacent the leading edge of the receiver 12 so that portions of the leader sheet and the carrier sheet lie between the film 11 and receiver 12, and the leading and trailing ends of the film 11 are, respectively, disposed adjacent the trailing and leading ends of the receiver sheet 12. The film pack is provided with a generally flat, rectangular pressure plate 50 located intermediate the film and the other portions of the film unit for supporting the film flatwise adjacent the inner surface of the forward wall 40 in position for exposure through the aperture 44. Pressure plate 50 includes a rolled end section 52 around which extends the bent back portion of the leader sheet 14 of each film unit, see FIGS. 4 and 5. Rolled end section 52 is provided for guiding film 11 around the end of the pressure plate and into superposed relation with its corresponding receiver sheet 12 in a manner to be hereinafter described. The major portion of first section 15 of the leader sheet 14, rupturable pod. mounted thereon, tapered section 16, and the leading end section 23 of the carrier sheet 19 are located behind the pressure plate 50 and between the latter and the receiver sheet 12. Pressure plate 50 is provided with lateral flanges 54 disposed adjacent side walls 4'1 of the container. The cover 46 is provided with spring fingers 56 biased inwardly for engaging the top of the lateral flanges 54 and urging pressure plate 50 toward the forward wall 40 to retain the film 11 in a predetermined plane for exposure.

The means forwithdrawing each film unit 10 from the pack 38 with the film 11 and receiver 12 superposed, and for advancing tapered end section 16 between a pair of pressure rollers, comprises a relatively narrow and elongated pull tab 60 adhesively secured at its tapered trailing end 60' to tapered end section 16 intermediate first section 15 and the point of attachment of the tapered end section to tapered wall portion 24 of carrier sheet 19. The adhesive bond between the trailing end of pull tab 60 and tapered end section 16 is such that it will provide sufficient resistance to the application of tension in a direction of the plane of the tapered end section. 24 to prevent it from becoming sheared apart, but when tension is applied to the pull tab in a direction at an angle to the tapered end section 16 the pull tab will readily peel from the end section 16. This adhesive bond may comprise a stripe coating of heat scalable adhesive on the trailing end of the pull tab as indicated at 60" in FIGS. 6 and 7. By virtue of this adhesive connection 60", so long as the pull tab and the film unit to which it is coupled are being moved in approximately the same direction the adhesive bond between the pull tab and end section 16 is subjected to a shear force and will not fail. This condition exists when the pull tab 60 is pulled from a camera to advance the end section or leader 16 between the pressure rolls of a camera in which the film pack is situated. However, when the direction of movement of the pull tab 60 diverges sufficiently from the end section 16, as it will after the end section has been fed through the pressure rolls of the camera and can be grasped to pull the film unit from the camera, the adhesive bond 60" between the leading end of the pull tab 4 force which causes the pull tab to separate from the tapered end section or leader 16. Since the manner in which the adhesive bond between the pull tab 60 and leading end section 16 is first subjected to a shear force and then a peeling force as it is pulled from the camera due to the manner in which it cooperates with the pressure rolls of the camera is well known in the prior art (see U.S.Pat. No. 3,161,516) such camera structure has not been disclosed.

Film pack 38 is provided with means for initially sealing the exposure aperture 44 against the admission of light until the pack has been loaded into the camera in which it is 1 to .be employed. This light sealing means comprises a cover sheet. 65 of a light impervious material located between the foremost film 11 and the forward wall 40 and extending across the exposure aperture 44. Cover sheet 65 extends around the curved end 52 of the pressure plate 50 and behind the same to a position adjacent the cover 46. It has a tapered leading end 66 which extends through the opening 45in the forward wall in the forward end of the pack and serves as aarneans. for withdrawing the cover sheetfrom the packafter the pack has been loaded into a camera. The pull tab of the first film unit of a pack is adhesively connected'to the cover sheet so that it will be pulled from 8.0 mil deep gravure roll and does not possess a tack which causes objectionable blocking when the pull tab product is rolled up or the film units are being assembled is shown in the following example:

Weight es Polyiloprene v 95 Methyl chloroform For proper functioning,the strength of the cohesive bond between pull tabs must. be within certain limits. If

it is too low the next pull tab will not be pulled out of tive. The term'strength as used here includes the effect of area, width of the leading edge of the bond, and the the camera when the cover sheet is withdrawn to ready I No. 3,161,516) the pull tabs of all of the film units in the pack, as well as the leading end of the cover sheet, extend outside of the pack. As a result,.if the camera user is not particularly careful to fold the ends of the pull tabs up against the end of the pack when loading ,thepack into the camera it often occurs that one .or more of the pull tabs can be caught or pinched between the camera back and the camera when the back is closed and the pack will malfunction- In; the film pack of the present invention, this problem is overcome since all of the pull tabs 60 are confined within the pack'and only the cover sheet extends therefrom, see FIGS. 4 and 5. To this end, and as best shown in FIGS. 5 and 6, the end of each pull tab is folded back or wrapped around the receiver sheet 12 of its film unit so that a first patch 75 of cohesive cement on the pull tab is superposed with a second patch 76 of cohesive cement on the pull tab of the preceding film unit or the cover sheet in the case of the pull tab of the first film unit to be exposed. The cohesive cement can be any of the materials of the self-adhering type, such well known pressure-sensitive, latex base, adhesives used in so called self-sealing envelopes, elastomers including styrene butadiene natural rubber disolved in benzene or heptane toluole, or polyisoprene disolved in methyl chloroform (1-1-1 tri chlorothane). Such materials can be coated directly on the pull tabs if they have sufficient tack or they can be applied to a base support which is then cut to proper shape and size and attached to the pull tabs. A cohesive material which can be successfully coated directly on the pull tab by an properties of thecohesive material. It follows that the cohesive bond between the pull tabs must have suffi cient shear strength to cause a succeeding pull tab to be pulled from the camera as a preceding pull tab is pulled out of the camera and a peel strength such that they will readily peel apart after the preceding pull tab is pulled completely from the camera. The force required to prematurely advance the next film unit decreases as film units are removed from the pack. As a-result the last few film units require the least pull for premature advance so that the peel strength between pull tabs must be lower than that limit. Two to 3 lbs. is a maximum. The shear strength of the bond must be high enough to advance the first pull tab when the safety cover is removed, e.g. approximately 0.5 lbs.

While the size and shape of the cohesive patches on the pull tabs may vary, it has been found that the use of two stripe coatings such as shown in FIGS. '6 and 7 gives very good results. It will be noted that here the two cohesive patches are in the form of stripes running transversely of the pull tab. The stripes of cohesive and 76 are of different width asshown to insure a con stant bond strength if there is some misalignment of the cohesive stripes in the, longitudinal direction during assembly. The advantage of such a construction will be appreciated when it is realizedthat in the assembly of the film packs eight film units are first stacked one on top of the other in an extended flatwise condition and the pull tabs are folded back upon their own receiver sheet 12 to bring the cohesive patch 75 on one into superposed relation with the cohesive patch 76 of the succeeding pull'tab. The cohesive bonds between pull tabs is then readily effected by applying pressure to the stack of film units in the area of the cohesive bonds. It has been found that a narrow pressure bar subjected to a pressure of 200-500 psi is satisfactory for effecting the cohesive bond between the pull tabs without adversely affecting the film, receiver or any other component of the film unit. v

After the cohesive bonds between the stacked film units is accomplished, the stack of assembled film units are folded around the pressure plate to the condition shown in FIGS. 4 and 5 and then the film units and pressure plate 50 are dropped into the container 39 and the cover is slid into place. In FIG. 7, the cohesive patches 75 and 76 are shown as consisting of two layers because it has been found to be advantageous toapply these in two thin layers instead of one thick layer. In

order to obtain rapid curing of the cohesive coating they are applied in rather thin layers and the first layer tends to soak into the support, particularly if the support is paper. The second layer is then required to obtain a cohesive patch on the surface of the pull tab which has the necessary cohesive characteristics.

To be sure that the pull tabs will fold back in proper alignment with one another during assembly of the pack it has been found desirable to fold each pull tab back over its receiver individually and crease the fold before they are stacked in a flatwise condition. This insures that the cohesive patches on the folded-back pull tabs will come into alignment without special attention being paid to the folding operation when the film units are stacked in a flatwise condition. Since as the film units are folded around the pressure plate there is a cer tain foreshortening of the pull tabs, when the pull tabs are initially folded back upon themselves and creased they are not necessarily folded tight against the end of the receiver 12 but the fold in the pull tab may be spaced about one thirty-second inch from the end of the receiver.

In order to prevent blocking of the pull tabs during the assembly operation, or during stocking in a stock roll form, and/or to reduce the friction between adjoining elements and reduce the pull necessary to withdraw a film unit from the pack, the top surface of the pull tab between the cohesive patches 75 and 76 and the back of the pull tabs are provided with a slip and/or release coating 100 and 101, respectively, see FIG. 7. The term blocking as used means the sticking together of adjoining layers of a stack or roll of product due to the tack of the cohesive material for a surface other than itself. It will be noted that the length of the slip or release coating 101 on the back of each pull tab is sufficient to embrace the two cohesive patches 75 and 76 on the other side of the pull tab. The slip and/or release coating used serves to reduce the friction between adjoining elements and reduce the pull force necessary to withdraw a film unit from the pack. There are numerous materials which can be used as slip and/or release agents, including organo-'siloxanes, oleamides, mixtures of alkyl silicones and an aryl silicone dissolved in a mutual solvent medium (70 percent acetone and 30 percent methanol) for said polymer. Examples of the most suitable slip and/or release agents found are as follows:

An organo silicone polymer sold by Stauffer-Wacker Silicone Corp., (SWS463) dissolved in methyl chloroform.

The last mentioned slip and release agent was found to be preferred over others tried since it was not subject to rub off, and when coated very thin will cure in 30 seconds at 160F.

If the inner surface of the safety cover sheet is coated with a slip agent to facilitate its withdrawal from the pack then a patch of cohesive cement should be placed thereon to cooperate with the patch of cohesive on the first pull tab in order to provide a satisfactory bond between the two. However, it has been found that cohesive cements suitable for'use on the pull tabs will have sufficient tack to adequately join the first pull tab to the cover sheet paper if it is not coated with a slip agent. Accordingly if a window is left in the slip coat on the cover sheet so that the cohesive patch on the first pull tab 60 will directly engage the cover sheet paper then no cohesive patch is required on the cover sheet. It follows from the above description that the tack characteristics of the cohesive cement are quite critical, particularly if the cohesive is coated directly on the pull tabs and/or cover sheet and must depend upon its tack property to adhere it to a surface. While a high tack property is desired for holding the cohesive to the pull tab, too high a tack might give objectional blocking when the film units are stacked during assembly or when the pull tab material is stored in roll form. The tack of the mentioned cohesive cements can be adjusted by the addition of tackifiers or detackifiers in different amounts. -Terpenes and polystyrenes are examples of tackifiers which can be used with the cohesive cements mentioned. Suitable detackifiers for these cements include starch, fumed silica, aluminum styrate and fumed alumina.

Should lateral misalignment when superposing the end of one pull tab 60 to an adjacent pull tab become a problem then the cohesive patches can be preferably narrower than the pull tab width as shown at 75' and 76 in FIG. 8. With this arrangement of patches a slight lateral misalignment of the patches of two adjacent pull tabs can occur without one of the cohesive patches contacting a material which is not to be moved with the pull tab. However, a full pull tab width cohesive stripe is possible providing the edges of the pull tab are notched at the cohesive strip 76" nearest the end of the' pull tab which is sealed to the leader end section 16 as shown in FIG. 9.

From the above description it will be appreciated that an advantage of having the pull tabs folded and attached to each other completely within the container 38 is that the pull tabs cannot possibly be pinched between the container and the camera or between the camera body and camera back as is possible with commercially available film packs. Another customer advantage is the additional gripping power offered by the cohesive coating on or near the end of the pull tab extending from the camera. The final assembly operation of attaching the pull tabs to each other is simplified since no sealing operation is required. The cohesive bond between selected layers of a stack of material is accomplished by pressure alone applied to the outer layers of the stack.

This invention has been described with reference to particular embodiments thereof but it will be understood that variations and modifications may be effected within the spirit and scope of the invention.

We claim:

1. A photographic film assemblage adapted for use in a camera, said film assemblage comprising in combination,

1. a plurality of film units arranged in stacked relation, each film unit including a leader for withdrawing the film unit from said stack and a pull tab coupled at one end to said leader for withdrawing said leader from the stack;

2. a container adapted to be inserted in a camera enclosing said stack of film units and having an opening through which said film units are movable in succession and through which the pull tab of only one film unit projects at any one time;

3. the free end of each of the pull tabs of said other film units being folded back upon itself toward the pull tab of the adjacent film-unit to an extent such that initially all of the pull tabs lie within the confines of said container and being adhesively connected in face-to-face relation to the pull tab of an adjacent film unit; said adhesive connection comprising a patch of cohesive cement on the surface of at least one of said pull tabs and forming a cohesive bond having a peel strength less than its shear strength.

2. A photographic assemblage as defined in claim 1, including a safety cover embracing the stack of film units and having a leading end extending through the opening in said container; the end of the pull tab on the film unit immediately adjacent said safety cover being adhered in face-to-face relation with saidsafety cover by a pressure-sensitive adhesive bond having a shear strength sufficient to withdraw said pull tab from said container as the safety cover is withdrawn from said container but weaker than the connection between said pull tab and the leader to which it is coupled so that withdrawal of the safety cover will not pull the first film unit from the container.

3. A photographic film assemblage as defined in claim 2, wherein the adhesive connection between said safety cover and the pull tab on the film unit immediately adjacent thereto comprises a stripe of cohesive material on each of the safety cover and the end of the pull tab which are brought into face-to-face contact when the pull tab is folded back upon itself toward the safety cover.

4. A photographic film assemblage comprising in combination,

l. a plurality of film units arranged in stacked relation, each film unit including a leader for withdrawing the film unit from said stack and a pull tab coupled at one end to said leader for withdrawing said leader from the stack;

2. a container enclosing said stack of film units and having an opening through which said film units are movable in succession and through which the pull tab of only one film unit projects at any one time; 3. the free end of each of the pull tabs of said other film units being folded back upon itself toward the pull tab of the adjacent film unit to an extent such that initially all of the pull tabs lie within the confines of said container, and v 4. the upper surface of each pull tab having two patches of cohesive material thereon, a first patch being adjacent the end of the pull tab attached to the leader and the second patch being adjacent the free end of the pull tab; the secondpatch of coheil %-l% i'c 83t8lvlllll'ili rlfsi3aifii'% sive material on the pull tab of the adjacent film unit when folded back upon itself toform a cohesive bond having a peel strength less than its shear strength. g

5. A photographic film assemblage as defined in claim 4, wherein the two patches'of cohesive material on each pull tab have a'different dimension longitudinally of the pull tab to insure a constant bond strength even if there is some misalignment of the cohesive patches in the longitudinal direction of the pull tabs when one is folded back upon'itself into face-toface contact with the one adjacent thereto. v

i 6. A photographic film assemblage as defined in claim 4, wherein that portion of the surface of the film unit located in superposed relation with said first patch of cohesive on the pull tab of an adjacent unit has a release coating thereon to prevent unwanted blocking of the film units together prior to the time the ends of the pull tabs are folded back against themselves.

7. A photographic assemblage as defined in claim 6, wherein the cohesive material is polyisoprene and the release coating is an oleamide in a cellulose acetate butyrate binder.

8. A photographic film assemblage as defined in claim 4, whereinthe two patches of cohesive material on each pull tab are narrower than its pull tab width to allow for some lateral misalignment when superposing the folded-back end of one pull tab to an adjacent pull tab without one of the cohesive patches contacting a part of the film unit which is not to be moved with the pull tab.

9. A photographic film assemblage as defined in claim 4, wherein the first patch of cohesive'material on 'a given pull tab is narrower than the width of the pull 

1. A photographic film assemblage adapted for use in a camera, said film assemblage comprising in combination,
 1. a plurality of film units arranged in stacked relation, each film unit including a leader for withdrawing the film unit from said stack and a pull tab coupled at one end to said leader for withdrawing said leader from the stack;
 2. a container adapted to be inserted in a camera enclosing said stack of film units and having an opening through which said film units are movable in succession and through which the pull tab of only one film unit projects at any one time;
 3. the free end of each of the pull tabs of said other film units being folded back upon itself toward the pull tab of the adjacent film unit to an extent such that initially all of the pull tabs lie within the confines of said container and being adhesively connected in face-to-face relation to the pull tab of an adjacent film unit; said adhesive connection comprising a patch of cohesive cement on the surface of at least one of said pull tabs and forming a cohesive bond having a peel strength less than its shear strength.
 2. a container adapted to be inserted in a camera enclosing said stack of film units and having an opening through which said film units are movable in succession and through which the pull tab of only one film unit projects at any one time;
 2. A photographic assemblage as defined in claim 1, including a safety cover embracing the stack of film units and having a leading end extending through the opening in said container; the end of the pull tab on the film unit immediately adjacent said safety cover being adhered in face-to-face relation with said safety cover by a pressure-sensitive adhesive bond having a shear strength sufficient to withdraw said pull tab from said container as the safety cover is withdrawn from said container but weaker than the connection between said pull tab and the leader to which it is coupled so that withdrawal of the safety cover will not pull the first film unit from the container.
 2. a container enclosing said stack of film units and having an opening through which said film units are movable in succession and through which the pull tab of only one film unit projects at any one time;
 3. the free end of each of the pull tabs of said other film units being folded back upon itself toward the pull tab of the adjacent film unit to an extent such that initially all of the pull tabs lie within the confines of said container and being adhesively connected in face-to-face relation to the pull tab of an adjacent film unit; said adhesive connection comprising a patch of cohesive cement on the surface of at least one of said pull tabs and forming a cohesive bond having a peel strength less than its shear strength.
 3. the free end of each of the pull tabs of said other film units being folded back upon itself toward the pull tab of the adjacent film unit to an extent such that initially all of the pull tabs lie within the confines of said container, and
 3. A photographic film assemblage as defined in claim 2, wherein the adhesive connection between said safety cover and the pull tab on the film unit immediately adjacent thereto comprises a stripe of cohesive material on each of the safety cover and the end of the pull tab which are brought into face-to-face contact when the pull tab is folded back upon itself toward the safety cover.
 4. A photographic film assemblage comprising in combination,
 4. the upper surface of each pull tab having two patches of cohesive material thereon, a first patch being adjacent the end of the pull tab attached to the leader and the second patch being adjacent the free end of the pull tab; the second patch of cohesive material on one pull tab being brought into face-to-face contact with the first patch of cohesive material on the pull tab of the adjacent film unit when folded back upon itself to form a cohesive bond having a peel strength less than its shear strength.
 5. A photographic film assemblage as defined in claim 4, wherein the two patches of cohesive material on each pull tab have a different dimension longitudinally of the pull tab to insure a constant bond strength even if there is some misalignment of the cohesive patches in the longitudinal direction of the pull tabs when one is foldeD back upon itself into face-to-face contact with the one adjacent thereto.
 6. A photographic film assemblage as defined in claim 4, wherein that portion of the surface of the film unit located in superposed relation with said first patch of cohesive on the pull tab of an adjacent unit has a release coating thereon to prevent unwanted blocking of the film units together prior to the time the ends of the pull tabs are folded back against themselves.
 7. A photographic assemblage as defined in claim 6, wherein the cohesive material is polyisoprene and the release coating is an oleamide in a cellulose acetate butyrate binder.
 8. A photographic film assemblage as defined in claim 4, wherein the two patches of cohesive material on each pull tab are narrower than its pull tab width to allow for some lateral misalignment when superposing the folded-back end of one pull tab to an adjacent pull tab without one of the cohesive patches contacting a part of the film unit which is not to be moved with the pull tab.
 9. A photographic film assemblage as defined in claim 4, wherein the first patch of cohesive material on a given pull tab is narrower than the width of the pull tab and/or the second patch of cohesive material to allow for some lateral misalignment when superposing the folded-back end of one pull tab to an adjacent pull tab without one of the cohesive patches contacting a part of a film unit which is not to be moved with the pull tab. 